Method for fabricating an optical integrated circuit

ABSTRACT

The present technique relates to a method for fabricating an optical integrated circuit amplifier with another type of optical integrated circuit. In optical networks, optical components exchange optical signals to communicate between different systems coupled to the optical components. The optical components may include optical integrated circuit amplifiers and other optical integrated circuits coupled together through optical paths. The optical integrated circuit amplifiers and other optical integrated circuits of the optical components are fabricated on the same substrate to reduce the cost of fabrication, maintenance and installation, while enhancing the performance of the optical component.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a divisional of application Ser. No. 10/894,268,which was filed on Jul. 19, 2004.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates generally to optical integrated circuitsand, more particularly, to fabricating an optical integrated circuitamplifier with another optical integrated circuit.

2. Description of the Related Art

This section is intended to introduce the reader to various aspects ofart which may be related to various aspects of the present inventionwhich are described and/or claimed below. This discussion is believed tobe helpful in providing the reader with background information tofacilitate a better understanding of the various aspects of the presentinvention. Accordingly, it should be understood that these statementsare to be read in this light, and not as admissions of prior art.

Processor-based systems are used in a wide variety of applications tosupport the communication of data. Such applications include personalcomputers, telephones, control systems, networks, and a host of consumerproducts. These systems are typically generic devices that include aprocessor to perform specific functions based on a software program.This program is stored in a memory device, such as dynamic random accessmemories (DRAMs), static random access memories (SRAMs) or othersuitable types of memories that are within the system and accessible tothe processor. Not only does the processor access memory devices toretrieve program instructions, but it also stores and retrieves datacreated during the execution of the program in one or more memorydevices.

Because it may be desirable for information to be transferred from onesystem to another system, networks may be utilized to facilitate theexchange of data. The networks may be configured to enable data to beshared across an office, a building, or any geographic boundary. Whilethese networks may utilize copper or wireless media, the network mayalso include optical technologies to increase the speed of the exchangeof data, broaden the available bandwidth, and extend the distancesbetween systems. In an optical network, optical fibers may carry opticalsignals having different wavelengths between different opticalcomponents, such as optical integrated circuits, which route and switchthe signals between the systems.

In fabricating optical integrated circuits, different materials arelayered together to form various structures to process the opticalsignals. For example, optical integrated circuits may be utilized tomultiplex signals, demultiplex signals, adjust power (attenuation) ofwavelengths on the signals, add and/or drop a desired wavelength or aset of wavelengths, filter a wavelength, switch the path of signals, andamplify signals. Accordingly, the optical integrated circuits enable thesystems to exchange data through the management of the signals overfibers in the optical network.

However, to process the signals in the optical component, the signalsare transferred from fiber to the optical integrated circuit and thenback to fiber once the signals are processed. The strength or power ofsignals may degraded in the conversion of signals between the fiber andthe optical integrated circuit as well as during the processing of thesignals in optical integrated circuit. As such, the signals are oftenamplified to increase the strength of the signals.

Accordingly, optical integrated circuit amplifiers are typically coupledto fiber and are a separate optical integrated circuit. Because theoptical integrated circuit amplifiers are separate from other opticalintegrated circuits, the cost of a system and the space it consumes aregreater than if these structures could be found in a single opticalcomponent. Further, the multiple connection points between the otheroptical integrated circuits and the optical integrated circuitamplifiers may degrade the performance of the system by introducingadditional loss at each connection point. Accordingly, an opticalcomponent that reduces the cost and space consumed, while improving theperformance, would be advantageous.

BRIEF DESCRIPTION OF THE DRAWINGS

The foregoing and other advantages of the invention may become apparentupon reading the following detailed description and upon reference tothe drawings in which:

FIG. 1 is a block diagram illustrating an exemplary optical network inaccordance with embodiments of the present invention;

FIG. 2 is a block diagram of two exemplary optical components of FIG. 1in accordance with embodiments of the present invention;

FIG. 3 is an exemplary embodiment of the optical component of FIG. 2 inaccordance with embodiments of the present invention;

FIG. 4 is an exemplary embodiment of the optical integrated circuitpre-amplifier of FIG. 3 in accordance with embodiments of the presentinvention; and

FIG. 5 is a process flow diagram illustrating the exemplary fabricationof the optical component of FIG. 2 in accordance with embodiments of thepresent invention.

DETAILED DESCRIPTION OF SPECIFIC EMBODIMENTS

One or more specific embodiments of the present invention will bedescribed below. In an effort to provide a concise description of theseembodiments, not all features of an actual implementation may bedescribed in the specification. It should be appreciated that in thedevelopment of any such actual implementation, as in any engineering ordesign project, numerous implementation-specific decisions are made toachieve the developers' specific goals, such as compliance withsystem-related and business-related constraints, which may vary from oneimplementation to another. Moreover, it should be appreciated that sucha development effort might be complex and time consuming, but wouldnevertheless be a routine undertaking of design, fabrication, andmanufacture for those of ordinary skill having the benefit of thisdisclosure.

Using the techniques described herein, optical integrated component(OIC) amplifiers may be fabricated along with other devices, which maybe other types of OICs, as a single integrated component to enhance theoperation of the resulting optical component (OC). Accordingly,different processing methods may be utilized to fabricate OICs and OICamplifiers, while reducing damage to either device. Further, the presenttechniques may provide flexibility in processing methods that utilizedifferent materials with varying properties for specific embodiments ofthe IOC amplifiers and/or the OICs.

Referring initially to FIG. 1, a block diagram of an exemplary opticalnetwork architecture is illustrated and designated using a referencenumeral 10. The optical network architecture 10 may enable varioussystems 12-18 to communicate with one another through optical components(OCs) 22-30. In this example, each of the systems 12-18 may communicateacross a first optical hub 36, a second optical hub 38, and/or a network40. The systems 12-18 may be telephony devices, computer systems,optical devices, personal computers (PCs), memory arrays, personaldigital assistants (PDAs), or other processor based devices.

The systems 12-18 may utilize OCs 20-30 to communicate with each other.For instance, the system 12 may utilize the OC 20, the system 14 mayutilize the OC 22, the system 16 may utilize the OC 24, and the system18 may utilize the OC 26. Accordingly, the OCs 20-26 may act as aninterface for the respective systems 12-18 to provide certain signals tothe systems 12-18 and transmit signals from the systems 12-18.Similarly, the OCs 28 and 30 may function as switches that map signalsbetween the optical hubs 36 and 38 and network 40, as discussed below.Further, each of the OCs 20-30 may include optical integrated circuits(OICs) to process the signals.

The OCs 20-30 may utilize the optical hubs 36 and 38 to gain access toeach other. The first optical hub 36 may provide access to the system 12through the OC 20 and the system 14 through the OC 22, while the secondoptical hub 38 may provide access to the system 16 through the OC 24 andthe system 18 through the OC 26. The optical hubs 36 and 38 may includeoptical media, such as optical fibers, that carry signals from thesystems 12-18 along with signals received at the OCs 28 and 30. Theoptical hubs 36 and 38 may be configured in a fiber ring with each ofthe OCs 20-30 on the optical hubs 36 and 38 being coupled to fiber. Eachof the optical hubs 36 and 38 may be connected to as many as “n”different systems based on the capacity of the OCs 28 and 30. Further,it should be noted that the optical hubs 36 and 38 may be configured asa group of point-to-point fibers to individual OCs 20-30, or acombination of the point-to-point and ring configurations.

Further, the OCs 28 and 30 may provide access to other OCs 20-26 and theoptical hubs 36 and 38 via a network 40. The network 40 may include acombination of hubs, switches, routers, or the like. The network 40 mayinclude a local area network (LAN), a wide area network (WAN), ametropolitan area network (MAN), a server area network (SAN), and/or acombination of these types of networks. It should be appreciated thatthe network 40 may assume other forms, such as a telecommunicationsnetwork, or may even provide network connectivity through the Internet,or a private network. Accordingly, the network 40 may provide accessbetween the systems 12-18, which may be dispersed geographically withrespect to each other.

To communicate between the systems 12-18, optical signals may beprocessed by the OCs 20-30 to manage the communication between thesystems 12-18. The signals may include various channels, wherein aspecific wavelength or range of wavelengths is assigned to each of thechannels. Each of the channels utilized by the systems 12-18 may be asubset of the wavelengths within certain wavelength bands. For instance,the channels may include wavelengths in the S-band, which spans fromabout 1450 nanometer (nm) to 1520 nm, the C-band, which spans from aboutthe 1530 nm to 1560 nm, and/or the L-band, which spans from about 1570nm to 1620 nm. Accordingly, the OCs 20-30 may be configured to managethe signals for the systems 12-18 based upon certain wavelengthsassociated with the assigned channels for each of the respective systems12-18.

The signals transferred over the fibers in the optical hubs 36 and 38and network 40 may be processed by the OCs 20-30 based on thewavelengths assigned to the systems 12-18. As noted above, each of theOCs 20-30 may include one or more OICs. The OICs may perform specificoperations on the signals or wavelengths within the signals for the OCs20-30. For instance, the OICs may process signals by multiplexingchannels, demultiplexing channels, adjusting power (attenuation) ofchannels, adding and/or dropping a channel or group of channels,filtering specific channels or group of channels, switching channels toanother fiber, and amplifying specific channels or signals. As aspecific example, the system 12 may be assigned a channel in the L-band,which includes the wavelengths from about 1570 nm to 1580 nm. The OC 20may remove signals within this assigned channel from the fiber in thefirst optical hub 36 and provide those signals to the system 12.Further, if the system 14 is assigned another channel in the L-band,which includes the wavelengths from about 1580 nm to 1590 nm, then theOC 28 may provide signals within the wavelength range of 1570 nm to 1590nm from the network 40 to the first optical hub 36. Accordingly, the OCs20-30 may be configured to manage or process signals for the systems12-18 based upon the wavelengths.

For the OCs 20-30 to manage the wavelengths in the optical hubs 36 and38 and network 40, the signals are transferred between the OCs 20-30 andthe fibers in the optical hubs 36 and 38 and network 40 for processingof the signals. The conversion of these signals is a lossy process thatreduces the power or strength of the signals being converted.Accordingly, the signals may be amplified to increase the signalstrength before processing in the OICs and/or after processing in theOICs. As such, it may be advantageous to have an OIC amplifierassociated with each OCs 20-30 or each of the OICs in the OCs 20-30.

The OIC amplifiers and the other OICs having other functions aretypically separate devices that are coupled together with fiber or othersuitable material. Because these devices are separate, the OICamplifiers and the other OICs may have higher loss than an integrateddevice, and the cost of the separate devices may be higher than thefabrication of an integrated device. For instance, if the connectionsbetween the OIC amplifiers and the other OICs are via fibers, then eachconnection may introduce a higher loss than a continuous waveguide in asubstrate. Further, the cost of fabricating the OIC amplifiers and theother OICs as a single device may reduce the cost in comparison toseparate devices because materials and processes may be shared in anintegrated device. Also, the combination of the other OIC and the OICamplifier on same chip has the potential to reduce the installationcosts associated with the installing the fibers, as well as maintenancecosts for repairing breaks in exposed fibers. In addition, the spaceconsumed by the other OICs and the OIC amplifiers is greater withseparate devices than the space consumed by an integrated component thathas other OICs and OIC amplifiers stacked together. The integration ofthe other OICs and OIC amplifiers in OCs 20-30 is further discussed inFIG. 2.

FIG. 2 is a block diagram of two exemplary optical components of FIG. 1in accordance with embodiments of the present invention. In thisdiagram, which is generally referenced by the reference numeral 48, twoOCs 20 and 22 may communicate via a fiber 50, which may be one of thefibers in the optical hub 36 (FIG. 1). The OCs 20 and 22 may provide acommunication path from the system 12 to the system 14. It should benoted that this diagram is merely used for exemplary purposes and any ofthe OCs 20-30 (FIG. 1) may be utilized in a similar manner.

The OC 20 may include a substrate divided into an OIC pre-amplifier 56,an OIC post-amplifier 58, and another type of OIC 52, such as an OIC formultiplexing, demultiplexing, adjusting the power, adding, dropping,filtering, and switching specific channels or signals, for example. TheOIC pre-amplifier 56 and/or the OIC post-amplifier 58 may be erbium (Er)doped waveguide amplifiers that include Er doped materials or ytterbium(Yb) doped waveguide amplifiers that include Yb doped materials.Further, as discussed above, the other OIC 52 may process signals bymultiplexing, demultiplexing, adjusting the power, adding, dropping,filtering, and switching specific channels or signals. The OICpre-amplifier 56 and the OIC post-amplifier 58 may exchange signals withthe other OIC 52 via optical paths 64 and 66. The optical paths 64 and66 may be structures or vias within the substrate, which are utilized tocouple the OIC pre-amplifier 56 and/or the OIC post-amplifier 58 withthe other OIC 52. Accordingly, the optical paths 64 and 66 may bewaveguides that guide signals between the OIC amplifiers 56 and 58 andthe other OIC 52.

Similar to the OC 20, the OC 22 may include a substrate divided into anOIC pre-amplifier 60, an OIC post-amplifier 62, and another type of OIC54. The OIC amplifiers 60 and 62 may be Er doped waveguide amplifiers orYb doped waveguide amplifiers, for example. Also, the OIC 54 may processthe signals in a manner similar to OIC 52, which is discussed above. TheOIC pre-amplifier 60 and the OIC post-amplifier 62 may exchange signalswith the other OIC 54 through optical paths 68 and 70, which are similarto the optical paths 64 and 66. Accordingly, the optical paths 68 and 70may be waveguides that guide signals between the OIC amplifiers 60 and62 and the other OIC 54.

By utilizing the OCs 20 and 22, signals may be generated from the system12 in a transmission phase and delivered to the system 14 in a receptionphase. In the transmission phase, the OIC pre-amplifier 56 may receive adata signal from the system 12 via a fiber 72 and receive a pump signalfrom a source 76 via a fiber 74. The source 76 may be laser or group oflasers that provide the pump signal within a selected wavelength orrange of wavelengths to amplify the data signal received from the system12. For instance, the source 76 may provide a 980 nm or 1480 nm signal,as the pump signal. The OIC pre-amplifier 56 may boost the data signalwith the pump signal and provide the amplified data signal to the otherOIC 52 for processing via the optical path 64. Then, the processedsignal may be provided to the OIC post-amplifier 58 via the optical path66 for further amplification with the pump signal that is received fromthe source 76 via the fiber 74. The OIC post-amplifier 58 may boost thedata signal, which has been amplified and processed, for transmission tothe system 14 via the fiber 50.

During the reception phase, the OIC pre-amplifier 60 may receive thedata signal from the fiber 50 and receive a pump signal from a source 78via a fiber 80. Similar to the source 76, the source 78 may be laserthat provides the pump signal within a selected wavelength or group ofwavelengths to amplify the wavelengths assigned to the system 14. TheOIC pre-amplifier 60 may boost the data signal with the pump signal andprovide the amplified data signal to the other OIC 54 for processing viathe optical path 68. Then, the processed signal may be provided to theOIC post-amplifier 62 via the optical path 70 for further amplification.The OIC post-amplifier 62 may also be coupled to the source 78 throughthe fiber 80. Accordingly, the OIC post-amplifier 62 may boost thesignal and provide the amplified processed signal to the system 14.

Advantageously, the OCs 20 and 22 may provide various costs savings,while enhancing the operation of the OCs 20 and 22 by boosting thesignal strength. First, the fabrication costs along with the spaceconsumed by the individual devices may be reduced because the OICamplifiers 56-62 and the other OICs 52 and 54 are fabricated on the samesubstrate for the respective OCs 20 and 22. As a result, the OICamplifiers 56-62 and other OICs 52 and 54 may share processes to reducefabrication costs. Secondly, the costs of installation and maintenancelabor for the OCs 20 and 22 may be reduced because each of the otherOICs 52 and 54 and associated OIC amplifiers 56-62 are integrated into asingle device, which reduces the fiber connections between the otherOICs 52 and 54 and respective OIC amplifiers 56-62. As such, the laborfor maintenance and installation of these additional fiber connectionsis eliminated for the OCs 20 and 22. Thus, the OCs 20 and 22 may provideamplified signals with less loss and increased signal strength, whilereducing the cost of fabrication, installation and maintenance.

While the integration of the OIC amplifiers 56-62 along with the otherOICs 52 and 54 may be formed on the same level of the substrate, thefabrication of the OIC amplifiers 56-62 with the other OICs 52 and 54may involve a layered fabrication process to provide flexibility in thefabrication of the other OICs 52 and 54 and the OIC amplifiers 56-62.For example, the OIC 52 may have a core material that includes certainproperties for its optimum performance. These properties may balancevarious parameters, such as bend radius, index of refraction,birefringence, wavelength filtering, reflective loss, and/or attenuationto provide specific optical performance for the OIC 52. Similarly, theOIC amplifiers 56 and 58 may have a core material that is doped with Erand/or Yb, and may be designed with different optical propertiesspecific to the optimal performance of the OIC amplifiers 56 and 58.These different core materials may cause variations in the opticalproperties, which may result in performance degradation of the other OIC52 along with the OIC amplifiers 56 and 58. Further, the thickness ofthe core material in the OIC amplifiers 56 and 58 may be different fromthe core material thickness in the other OIC 52. As a result,fabricating the OIC amplifiers 56 and 58 on a different level than theother OIC 52 may provide flexibility in the selection of materials andprocesses, which may maintain the optical properties of the other OIC 52and the OIC amplifiers 56 and 58. The OC 20 with the OIC amplifiers 56and 58 and the other OIC 52 on different levels of a substrate may befurther described below in FIG. 3.

FIG. 3 is an exemplary embodiment of the optical component of FIG. 2 inaccordance with embodiments of the present invention. In this diagram,which is an exemplary embodiment of OC 20, the other OIC 52 may befabricated on different layers of a substrate 86 from the OICpre-amplifier 56 and OIC post-amplifier 58. The substrate 86 may includedifferent portions or structures, which are utilized to receive thefibers 50, 72 and 74 (FIG. 2), couple the OIC amplifiers 56 and 58 tothe other OIC 52, and process the data and pump signals. Beneficially,the substrate 86 may fabricated to enable the selection of materialsthat have specific properties for the different structures 88-112, whichform the OIC amplifiers 56 and 58 and the other OIC 52.

The OIC pre-amplifier 56 may include a first fiber connection structure88, a first waveguide division multiplexer (WDM) 90, a firstamplification structure 92, a first inverse WDM 94, and/or a firstcoupling structure 96. The first fiber connection structure 88 may beutilized to receive the fiber 72 from the system 12 and the fiber 74from the source 76 (FIG. 2). For instance, the first fiber connectionstructure 88 may utilize mechanical alignment, optical modetransformers, grating structures, or other suitable structures to couplethe fibers to the substrate 86. The first WDM 90 may combine the signalsfrom the fibers to provide the first amplification structure 92 with asingle signal that includes the data and pump signals. In the firstamplification structure 92, the pump signal excites a doped material,which is discussed below, to amplify the data signal passing through theamplifier structure. The first inverse WDM 94 may receive the combinedsignal and split the amplified data signal from the pump signal toprovide the amplified data signal to the first coupling structure 96.The first coupling structure 96 may be a waveguide that adjusts the pathof the amplified data signal and the pump signal to maintain the opticalproperties of the signals. The first coupling structure 96 may bedesigned based upon various geometrical structures that are utilized tomaintain a bend radius to prevent excessive attenuation. While theamplified data signal may be provided to the optical path 64, the pumpsignal in the first coupling structure 96 may be redirected to the firstamplification structure 92 through the first inverse WDM 94 to furtherstrengthen the signals or may be provided to another structure withinthe substrate 86. Thus, from the first coupling structure 96, theamplified data signal may be provided to the optical path 64 connectedbetween the OIC pre-amplifier 56 and the other OIC 52.

The OIC 52 may include a receiving structure 98, an OIC structure 100,and a delivery structure 102. The receiving structure 98 may receive theamplified data signal from the optical path 64. Similar to the couplingstructure 96, the receiving structure 98 may be a waveguide that adjuststhe path of the amplified data signal to maintain the optical propertieswithout resulting in excessive attenuation. The OIC structure 100receives the amplified data signal from the receiving structure 98 andprocesses the amplified data signal. The OIC structure 100 may includevarious structures that process the signals by multiplexing wavelengths,demultiplexing wavelengths, adjusting power (attenuation) of signals,adding and dropping a wavelength or group of wavelengths, filteringspecific wavelengths or group of wavelengths, switching signals toanother fiber, and/or amplifying specific wavelengths or signals, asdiscussed above. Then, the delivery structure 102, which may be similarto the receiving structure 98, may provide the processed signal to theOIC post-amplifier 58 via the optical path 66.

The OIC post-amplifier 58 may include a second coupling structure 104, asecond WDM 106, a second amplification structure 108, a second inverseWDM 110, and/or a second fiber connection structure 112. Each of thesestructures may be similar to the structures discussed above with regardto the OIC pre-amplifier 56. The second coupling structure 104 mayreceive the processed signals from the optical path 66. The second WDM90 may combine the processed signal from the other OIC 52 with a pumpsignal, such as the pump signal from the source 76 (FIG. 2), to providethe second amplification structure 108 with a single signal. The pumpsignal may be provided via the first fiber connection structure 88 orvia a fiber from the source 76 (FIG. 2) coupled to the second fiberconnection structure 112. The second inverse WDM 110 may receive thesignal and split the processed signal to be provided to the second fiberconnection structure 112 from the pump signal. The second fiberconnection structure 112 may be a waveguide that adjusts the path of theprocessed signal and pump signal to reduce excessive attenuation. Fromthe second fiber connection structure 112, the signal may be provided tothe fiber 50. Accordingly, the exemplary materials utilized in thestructures 88-96 of the OIC pre-amplifier 56 are shown in greater detailin FIG. 4.

FIG. 4 is an exemplary embodiment of the pre-amplifier of FIG. 3 inaccordance with embodiments of the present invention. In this diagram,exemplary materials utilized within the structures 88-96 of the OICpre-amplifier 56 are shown. These materials may be fabricated throughdifferent processes to form the structures 88-96 that receive thesignals, amplify the signals, and provide the signals to the other OIC52 via the optical path 64 (FIG. 2). Beneficially, by having the OICpre-amplifier 56 fabricated on a different level of the substrate 86,the selection of materials for the OIC pre-amplifier 56 may be based onthe specific properties for the structures 88-96 of the OICpre-amplifier 56. It should be noted that the materials utilized for thestructures 98-102 of the other OIC 52 and the structures 104-112 of theOIC post-amplifier 58 (FIG. 2) may be fabricated in a similar manner ondifferent levels of the substrate 86 to provide flexibility in theselection of those materials, as well.

Within the OIC pre-amplifier 56, various materials may be utilized toprovide specific optical properties. For instance, a core material 116and a cladding material 118 may be deposited over the substrate 86 andpatterned through various processes. The core material 116 may includean optically transparent material, such as silica glass or ceramicmaterials that have a high refractive index, while the cladding material118 may include a material with a low refractive index. As a specificexample, the core material 116 may be an aluminum oxide Al₂O₃ or yttriumoxide Y₂O₃, while the cladding is silicon dioxide SiO₂ Also, a dopedcore material 120 may be utilized, which may include the core material116 doped with Er or Yb ions to improve the amplification of the datasignal. Further, an index matching fluid 122 may be deposited in a firstgroove 124 and a second groove 126 to match the refractive index of thefibers, such as the fibers 72 and 74 (FIG. 2), with the core material116. This reduces loss and back reflection at the coupling of the fibersand the core material 116. Accordingly, each of these materials 116-122may be utilized to provide the specific optical properties for thestructures 88-96.

Based on the specific materials 116-122, the structures 88-96 may befabricated in specific configurations. For instance, the first fiberconnection structure 88 may include grooves 124 and 126 to align thefibers with the core material 116. The first WDM 90 may be an opticalcoupler that combines the core material 116 associated with the grooves124 and 126, while the first inverse WDM 94 may be an optical splitterthat separates signals, such as the data signal and the pump signal. Thefirst amplification structure 92 may include a specific length of thedoped core material 120 to amplify the signal received from the firstWDM 90. The first amplification structure 92 may include geometricshapes, such as folded spiral circuits, continuous spirals loops orarcs, to extend the length of the doped core material within a smallerfootprint. The geometric shapes of the first amplification structure 92may be limited by the geometry and associated bend radius in relation tothe wavelengths of the signals. Similarly, the first coupling structure96 may include different geometric shapes utilized to guide the signalsfrom the OIC pre-amplifier 56 level to the other OIC 52 level of thesubstrate 86. As an example, the first coupling structure 96 may alsoinclude a loop that guides the pump signal back into the amplifierstructure 92 via the inverse WDM 94 and an arc that guides the amplifieddata signal to the optical path 64. The fabrication of the OC 20 (FIG.3) is discussed below in FIG. 5.

FIG. 5 is a process flow diagram illustrating the exemplary fabricationof the optical component of FIG. 2 in accordance with embodiments of thepresent invention. The process flow diagram is generally referred to byreference numeral 130. In this diagram 130, the OC, which may be any ofthe OCs 20-30 (FIG. 1), may be fabricated to integrate one or more OICamplifiers along with one or more OICs in the OC. As discussed above,the OCs may include OICs, such as the other OICs 52 and 54 (FIG. 2),along with the one or more OIC amplifiers, such as the OIC amplifiers56-62 (FIG. 2). The OICs and amplifiers may be fabricated on differentlevels of a substrate for an OC. Beneficially, by utilizing twodifferent levels, the OICs and amplifiers may be designed independently,which enables the selection of material having specific properties forthe amplifiers and the OICs.

The process begins at block 132. At block 134, the OIC may be fabricatedon the substrate, which may be the substrate 86 (FIG. 3). Thefabrication of the OIC may include various process steps, such asdepositing materials on the substrate, patterning these materials andannealing the patterned material along with the substrate to form thespecific OIC. For example, the fabrication processes may includechemical vapor deposition, physical vapor deposition, dry etching, wetetching, ion implantation, rapid thermal annealing, and/orphotolithographic processes to form the structures for the OIC. At block136, a cladding material may be deposited over the substrate and the OICstructure. As discussed above, the cladding material may include amaterial low refractive index, such as a silicon oxide (SiO₂), adielectric material, or other suitable material.

Once the cladding material is deposited, the fabrication of theamplifier may begin, as shown in block 138. The amplifier fabricationmay include additional fabrication process steps, similar to thosediscussed above. At block 140, the interconnections, which may be theoptical paths 64-70 (FIG. 2), between the amplifier and the OIC may becreated through additional fabrication processes that may includeetching the cladding material and depositing a glass or ceramic materialto provide an optical path between the amplifier and the OIC. Then, atblock 142, the amplifier may be further processed to form theconnections with optical fibers, which may be the fibers 50, 72, 74, 80and 82 (FIG. 2). Accordingly, the process ends at block 144.

Alternatively, it should be appreciated that the OCs, such as the OCs20-30 (FIG. 1), may include different configurations. For example, theOC 20 may be fabricated with the OIC pre-amplifier 56, but the OICpost-amplifier 58 may not be part of the OC 20. In this configuration,the signal may be transferred from the other OIC 52 to the fiber 50. Asanother example configuration, the OC 20 may include the OICpost-amplifier 58, but the OIC pre-amplifier 56 may not be part of theOC 20. In this configuration, the signal may be transferred from thesystem 12 to the other OIC 52 via the fiber 72 for processing withoutamplification. Then, the signal may be amplified by the OICpost-amplifier 58 after being processed by the other OIC 52.Accordingly, as discussed above, each of these alternativeconfigurations may be formed with similar fabrication processes and mayprovide the advantages discussed above. Thus, it should be appreciatedthat the OCs, such as the OCs 20-30 (FIG. 1), may include differentconfigurations.

While the invention may be susceptible to various modifications andalternative forms, specific embodiments have been shown by way ofexample in the drawings and will be described in detail herein. However,it should be understood that the invention is not intended to be limitedto the particular forms disclosed. Rather, the invention is to cover allmodifications, equivalents and alternatives falling within the spiritand scope of the invention as defined by the following appended claims.

1. A method for fabricating a device, the method comprising: forming afirst optical integrated circuit on a substrate; forming a secondoptical integrated circuit over the first optical integrated circuit,wherein at least one of the first optical integrated circuit and thesecond optical integrated circuit is an amplifier; and forming anoptical path to couple the first optical integrated circuit and thesecond optical integrated circuit.
 2. The method, as set forth in claim1, wherein the first optical integrated circuit is formed on a firstlevel of the substrate and the second optical integrated circuit isformed on a second level of the substrate
 3. The method, as set forth inclaim 1, comprising depositing a cladding material between the firstoptical integrated circuit and the second optical integrated circuit. 4.The method, as set forth in claim 3, comprising etching a portion of thecladding material to expose a portion of the first optical integratedcircuit to form the optical path.
 5. The method, as set forth in claim1, comprising depositing a ceramic material to form the optical path. 6.The method, as set forth in claim 1, comprising coupling the amplifierto a fiber.
 7. The method, as set forth in claim 1, is performed in therecited order.
 8. A method of manufacture comprising the steps of: A)providing a substrate; B) disposing a layer on the substrate; C) etchingthe layer; D) repeating steps B) and C) to form a first optical deviceand a second optical device on the substrate, wherein the first andsecond optical devices are in different layers on the substrate; and E)providing an optical path between the first and second optical devices.9. The method of claim 8, wherein the optical path between the first andsecond optical devices is a via.
 10. The method of claim 8, wherein atleast one of the first and second optical devices is an amplifier. 11.The method of claim 8, wherein layering material on the substratecomprises layering doped material.
 12. The method of claim 12, whereinthe doped material comprises erbium.
 13. The method of claim 12, whereinthe doped material comprises ytterbium.
 14. The method of claim 8,wherein at least one of the first and second optical devices is awavelength division multiplexer.
 15. The method of claim 8, wherein theoptical path comprises a waveguide.
 16. A technique for fabricatingoptical integrated circuits comprising: forming a first optical deviceand a second optical device on different levels of a substrate, whereinat least one of the first and second optical devices is an amplifier;and providing an optical path to couple the first and second opticaldevices.
 17. The technique of claim 16 wherein providing an optical pathto couple the first and second optical devices comprises providing awaveguide.
 18. The technique of claim 16 wherein providing an opticalpath comprises providing a via.